The present invention relates to a metal plate having beads intersecting together, in particular a structure of a metal plate at a portion where the beads intersect.
An internal combustion engine is provided with a plurality of holes therein, such as cylinder bores, water holes, oil holes, bolt holes, push rod holes and so on. Some holes are securely sealed therearound to prevent leakage of fluid from the holes. For this purpose, the gasket is provided with specific sealing means around the holes to securely seal therearound.
In a metal laminate gasket formed of a plurality of metal plates, beads are often formed on the metal plate as sealing means around the holes to be sealed. When the gasket with the bead is tightened, the bead is compressed to form a surface pressure thereat to seal around the hole.
In a gasket, sometimes, holes to be sealed are located very close to each other. In this case, it is impossible to form a separate bead for each hole, but the adjacent beads are combined, and a common portion of the beads is eliminated. As a result, the two beads are intersected together.
When the two beads intersect, the intersecting portion of the two beads becomes eventually large. Therefore, when a plate with the intersecting portion of the two beads is compressed, the intersecting portion can not provide surface pressure equal to that formed on the rest of the beads. The surface pressure at the intersecting portion is generally weaker than that at the rest of the beads.
Also, since the intersecting portion is large, when the bead is compressed, equal tightening pressure may not be applied to the entire intersecting portion, i.e. eccentric stress may be locally formed on the intersecting portion. Accordingly, the surface pressure on the intersecting portion may be partly different, so that leakage may occur through a weak surface pressure portion in the intersecting portion.
In U.S. Pat. No. 4,861,047, a depression is formed at a middle of an intersecting portion of the beads to extend downwardly therefrom. The depression at the intersecting portion provides stiffness at that portion, so that the intersecting portion can provide surface pressure substantially equal to that at the rest of the beads.
In U.S. Pat. No. 4,869,515, a depression is formed at an intersecting portion of two beads. The depression extends from one edge portion of the bead to reduce the area of the intersecting portion.
In Japanese Utility Model Publication No. 4-50762 published on Apr. 28, 1992, an intersecting portion of two beads is formed to have a large area, so that a high pressure portion is formed at a part of the intersecting portion.
The above mechanisms operate as intended. However, when the intersecting portion of the beads is compressed, local eccentric stress may be formed at the intersecting portion to cause leakage of fluid.
Therefore, one object of the invention is to provide a metal plate with an intersecting portion of the beads, wherein the beads can substantially provide equal surface pressure throughout the entire area of the beads including the intersecting portion thereof when compressed.
Another object of the invention is to provide a metal plate as stated above, wherein local eccentric stress is not substantially formed at the intersecting portion of the beads when compressed.
A further object of the invention is to provide a metal plate as stated above, which can be formed easily and economically.
Further objects and advantages of the invention will be apparent from the following description of the invention.